Solid detergent



'Ju1y31,1'934. G, s, @ANS 1,968,753

SOLID DETERGENT Filed Jan. 2S, 1953 s sheds-sheet 1 TIME MINUTES INVENTOR BY y v ATTORNEYS SOLID DETERGENT um? i A l l; i lNvNToR ATTORNEYS July 31,1934. G. s. EVANS SOLID DETERGENT Filed Jan. 26, 1933 INVENTOR ATTORN EY I `Patented July 3l, 1934 v y l d I! UNITED STATES PATENTl OFI-ica l Lacasse soun nE'rEaGENT George S. Evans, Bronxville, Nl Y., assignor to I The Mathieson Alkali Works, Inc., New York, N. Y., a corporation of Virginia Application January 26, 1933, Serial No. 653,618 8 Claims. (Cl. 87-5) This invention relates to the manufacture of washing machine of the type referred to above cakes of detergent material and the invention is varies widely depending upon the condition of the particularly concerned with the production of dishes being washed and the hardness and temcakes of this character that are especially useful peratureof the wash water. For any given condiin conditioning the wash water in dish-washing tions there is a limited economic range of chem- 50 machines. The invention is primarily concerned ical strength between the maximum and miniwith the production of detergent cakes which go vmum strengths obtaining when looseor readily into solution in waterat a substantially constant soluble detergents are added tol the wash water rate throughout the dissolving period whereby at intervals in accordance with the practice here- 10 thealkalinity of the wash water can be maintofore employed. An alkalinity of between 75 65 tained within a certain desirable range, and 150 grains'per gallon is usually needed to In the operation of ordinary dish-washing mainsure thorough celansing of the dishes under chines, such as those used in hotels and restauaverage conditions. An excess of alkali in the rants, it is customary .toadd to the re-circulating re-circulating water is objectionable because of l5 water quantities of nonforming detergents such the tendency of the alkali to convert starchy maas soda ash, caustic soda or tri-sodium phosphate terials into a kind of glue which forms a sticky crystals or mixtures of such materials, the de-` deDOSit Orl the dSheS not ee-Sily remved by the tergent compound being added to the water in rinse water. On the other hand, if the alkalinity loose 0r powder form. The standard dish--wash-` of the wash Water is too low it is necessary to ining machine, as adapted to restaurants having a. crease materially both the Washing and rinsing seating capacity up to one hundred and fty to periods in order to cleanse the dishes thoroughly. two hundred, consists of a water tank of approx- The use 0f detergent material in DOWder 0r 100s@ imately fifteen gallon capacity with an overflow form is objectionable because when a charge of outlet, circulating pump, sprays and dish racks, this material is iirst added the alkalinity-of the all encased and connected to the water system. wash water is excessive and this makes it dil- 80 Where'gr'eater capacity lis required, two or three cult to cleanse the dishes properly and large quanof these machines are employed or machines of titles of the chemical are soon discharged through larger capacity are used the capacity being in the overilow without having perfrmed any useful multiples of fifteen gallons. In starting up such function. The concentration of the chemical is a dish-washing machine it is customary first to rapidly reduced until the amount of detergent 35 ll the tank withhot waterand then add a chargel material in the water is inadequate and another of the detergent compound. Ordinarily about charge Of the Compound must be added. The alone-half pound of the chemical is added to a fkelinity 0f the WeSh Water iS Within the desired teen gallon tank, givinga chemical strength of aprange only throughout a relatively Smell Dertien proximately 233 grains per gallon, and this is of the operating cycle. 90

supplemented by periodic additions at l5 to 45 One of the objects 0f llike 'present inventionv iS minute intervals during the operating period. to provide detergent material in a form such The fresh water employed for the purpose of that the eiliciensy of dish-Washing machines and rinsing the dishes replaces a portion of the rethe like may be substantially increased. In gen- $0l circulating water and a corresponding quantity of leral this object is attained by DrOVidrlg Cakes 01' 95 the re-circulating water is discharged through an briquettes of detergent material of such congoverilow pipe, carrying off any solids floating on uration and density 'that the detergent matethe surface as well as a portion ofthe detergent rial goes into solution in the dish-washing macompound. The volume of ,rinse water added chine at a rate such that the alkalinity of the during each cycle of operation is generally equal wash water remains within the desired range 100 to one-sixth or one-eighth of the tank capacity so of-say 75 to 150 grains per gallon of wash water that the volume of tank water is replaced by rinse throughout a considerable portion` of the operatwater with about seven cycles or more of operaing cycle of the machine. In preparing the detion. It is thus apparentl that the chemical tergent cakes I prefer to fuse the detergent ma-l strength of the re-circulating water is rapidly diterial andvthen cast this fused material into cake 105 luted both by consumption .in the washing opform, preferably although not necessarily, in a erations and by beingy carried of! in the overchilled mold which insures the production of flow water. cakes of high density. The form of the mold is The quantity of detergent compound required preferably such as to provide cakes having a ratio in properly cleansing dishes in the ordinary dishof surface area to volume or weightsuch that the lll)- average solubility rate in circulating water at 120 F. is between 3 and 41/2 grams per minute for each 100 square centimeters of original surface area of the cakes. In general, this ratio of area in square centimeters to weight in grams is between .4 and .9, the ratio being preferably limited to between .4 and .5. I prefer to employ metal molds for such molds are capable of absorbing the heat in the fused mass within the nicld at a rapid rate with the result that the cast cakes have a high density. Such molds may be referred to as chilled molds and it is'to be understood that any type of chilled mold may be employed where high density cakes are desired.

Where the cakes consist essentially of soda ash or mixtures of soda ash and tri-sodium phosphate or soda ash and sodium silicate the best results for the purpose described above are obtained when the cakes are of such size that their weight is between 90 and -600 grams. If cakes of this weight are cast in semi-spherical form, or in any other form having substantially the same ratio of surface area to volume, the average solubility rate of the cakes in circulating water at 120 F. is within a range of 3 to 41/2 grams per minute for each 100 square centimeters of original surface area of the cakes. When such cakes are used in the ordinary dish-washing -machine having a capacity of 15 gallons the alkalinity of the water is within the range of 'l5 to 150 grains per gallon throughout the major portion of the total period required for completely dissolving the cakes. By utilizing the present invention it is entirely feasible to maintain the alkalinity of the wash water within the desired range throughout eighty per cent of the time required for completely dissolving the detergent material, and excessive alkalinity can be avoided at all times.

The characteristics and-advantages of my invention will be more apparent upon considering the accompanying drawings of which Fig. 1 is a graph showing the solubility characteristicsof cakes of fused soda ash of various sizes;

Fig. 2 is a graph showing the area per 100 grams and the solubility rate per 100 square centimeters of original surface area of fused soda ash'cakes and Fig. 3 is a graph showing the alkalinity of the wash water in a 15 gallon capacity dish-Washing machine, the graph showing the results obtained by the use of one embodiment of the present invention as compared with the use of loose soda ash.

Referring to Fig. 1 of the drawings the several curves represent the alkali content of the wash water in a 15 gallon capacity dish-washing machine operated with a continuous flow of fresh water at the rate of one gallon per minute. The curve A represents the condition obtaining when a charge of 8 ounces or 226%; grams of loose soda ash is added to the 15 gallon tank. This 8 ounce charge was dissolved immediately, as indicated by the small circle at the top of the curve A, giving an alkalinity of somewhat over 23,0 grains per gallon and during 45 minutes of operation the alkalinity was reduced to below-15 grains per gallon. During the initial portion of this operating cycle the alkalinity of the water was excessive,- considerably more than 150 grains per gallon and the alkalinity was within the desired range of 75 to 150 grains per gallon during a comparatively small portion of the operating period of 45 minutes.

Curve Curve Curve Curve Curve Curve The small circle on each curve represents the time at which theA fused cake of soda ash was completely dissolved. It will be noted that the total time required for dissolving each of the cakes is substantially the same and that for the cakes weighing more than 600 grams the dissolving rate is excessive during a substantial portion of the dissolving period. This indicates the desirability of limiting the size of the cake to a range within to'600 grams and it will be noted that as to cakes within this range the rate of going into solution is substantially constant throughout the major portion of the period required for the cakes to be completely dissolved. The cakes represented by the curves 1 to 6 of Fig. 1 were cast in an iron mold of semispherical shape.

The curves A and B of Fig. 2 represent respectively the surface area in square centimeters per grams for cakes of fused soda ash of the type represented by the curves l to 6 of Fig. 1, and the rate of solution of such cakes in grams per 100 square centimeters of surface area per minute. From these curves A and B it will be noted that for the cakes having a weight of 90 grams to 642 grams the rate of solution is within the range of approximately 3 grams per 100 115 square centimeters of surface area to 4 and $5 grams per 100 square centimeters,and it has been found that cakes of fused soda ash, or of mixtures of detergent materials consisting essentially of fused soda ash and tri-sodium phosphate, having this average rate of solution in circulating water at a. temperature in the neighborhood of F., provide the desired alkalinity.

In Fig. 3 the curve A represents the alkalinity of the wash water in a 15 gallon capacity dishwashing machine when charges of 2261/2 grams `of loose soda ash are added at 40 minute intervals, and the curve B represents the alkalinity when 2261/2 gram cakes of fused soda ash are added to the washing machine tank at 40 minute intervals. It will be noted that when the loose soda ash is employed the alkalinity is excessive throughout the initial portion of the cycle and that when the fused cakes of soda ash are used the alkalinity is never in excess of 150 grains per gallon. Furthermore' when the fused cakes are employed the alkalinity remains within the desired range of 75 to 150 grains per gallon throughout the major portion of the cycle. The cakes of fused soda ash represented by the curve'B of Fig. 3 were made by casting the molten material in metal molds of semi-spherical shape. A

'I'he fused cakes of detergent material may consist entirely of soda ash, or of mixtures of soda ash and tri-sodium phosphate and if desired from 1 to 10 per cent by weight of sodium silicate may be added to the mixture, or to the Soda ash where no tri-sodium phosphate is used. The soda ash and tri-sodium phosphate may be mixed 159 in proportions such that the tri-sodium phosphate represents from 10 to 70 per cent by weight and preferably the percentage of 4tri-sodium phosphate is between 40 and 60 per cent by weight.-

It is to be understood that my invention is not limited to the specific embodiments thereof illustrated and described but includes such modiform suitable for maintaining the proper degree of alkalinity of the wash water in dish washing machines comprising sodav ash as a major ingredient, said cake having a ratio of surface area in square centimeters to weight in grams between .4 and .5.

3. A fused detergent alkaline salt body of approxmately semi-spherical shape and suitable for maintaining the proper degree of alkalinity of the wash water in dish washing machines comprising vsocia ash as a major ingredient, said cake having a ratio of surface area in square centimeters to Weight in grams between .4 and .9. l

4. A fused detergent alkaline salt mixture in cake form suitable for maintaining the proper degree of alkalinity of the wash water in dish washing machines comprising as major ingredients soda ash and tri-sodium phosphate blended l in proportions such that the tri-sodium phosphate represents 10 to 76 per cent of the total Weight of these ingredients, the cake having a ratio of surface area in square centimeters to weight in grams between .4 and .9.

.5. A fused detergent alkaline salt mixturein phate and sodaash.

cake form suitable for maintaining the proper degree of alkalinity of the wash water in dish washing machines comprising as major ingredients soda ash and sodium silicate blended in proportions suchl that the sodium silicate represents l to 10 per cent of the total weight of these ingredients, the cake having a ratio of surface area in square centimeters to weight in gram's between .4 and .9.

6. A fused detergent; alkaline. salt mixture in cake form suitable for maintaining the proper degree of alkalinity of the wash water in dish washing machines comprising as major ingredients soda ash and tri-sodium phosphate blended in proportions such that the tri-sodium phosphate represents 40 to 60 per cent of the total weight of these ingredients, the cake having a ratio of surface area in square centimeters to weight in grams between .4 and .9.

7. A fused detergent alkaline salt mixture in cake form suitable for maintaining the proper degree of alkalinity of the .wash Water in dish washing machines comprising as major ingredients soda ash, tri-sodium phosphate and sodium silicate blended in proportions such that the trisodium phosphate represents 10 to 70 per cent of the total weight of soda ash and tri-sodium phosphate and the sodium silicate represents 1 to 10 per cent of the total weight of tri-sodium phos-g 8. A fused detergent Aalkaline salt bodyv of semi-l spherical shape and suitable for maintaining the proper degree of alkalinity of the wash waterin dish washing machines comprising soda ash as amajor ingredient and having a weight in grams of between 90 and 600 and having an average solubility rate in circulating waterv at degrees Fahrenheit of between 3 and 41/2 grams per minute per 100 square centimeters of original surface area.

GEORGE S. EVANS. 

